Long Term Evolution (LTE for short) is Long Term Evolution of the Universal Mobile Telecommunications System (UMTS) technology standards that is formulated by the 3rd Generation Partnership Project (3GPP for short) organization. Key technologies such as Orthogonal Frequency Division Multiplexing (OFDM for short) and Multiple Input Multiple Output (MIMO for short) are introduced into the Long Term Evolution, obviously increase spectral efficiency and a data transmission rate, and have been widely developed in recent years. A Long Term Evolution-Advanced (LTE-A for short) system is a further evolved and enhanced system of an LTE system. In the LTE-A system, to satisfy a requirement of the International Telecommunication Union for a peak data rate of the fourth generation communications technology, a carrier aggregation (CA for short) technology is introduced, and is also referred to as a spectrum aggregation technology or a bandwidth extension technology. In carrier aggregation, spectrums of two or more component carriers are aggregated to obtain a wider transmission bandwidth, and the spectrums of the component carriers may be adjacent continuous spectrums, or may be nonadjacent spectrums within a same frequency band or even discontinuous spectrums within different frequency bands. LTE Rel-8/9 user equipment (UE) can access only one of the component carriers to receive and send data. However, LTE-A user equipment may access, according to a capability and a service requirement of the user equipment, multiple component carriers at the same time to receive and send data.
The LTE supports two duplex modes: frequency division duplex (FDD for short) and time division duplex (TDD for short). For the FDD, downlink and uplink transmission are performed on different carriers. For a TDD system, uplink and downlink transmission are performed on a same carrier at different times. Specifically, a carrier includes a downlink subframe, an uplink subframe, and a special subframe. The LTE currently supports seven types of different TDD uplink and downlink configurations.
The LTE implements an error detection and correction function by using a hybrid automatic repeat request (HARQ for short) mechanism. A downlink is used as an example. After UE receives a physical downlink shared channel (PDSCH for short), if the physical downlink shared channel is correctly received, the UE feeds back an acknowledgement (ACK for short) on a physical uplink control channel (Physical Uplink Control Channel, PUCCH for short); or if the physical downlink shared channel is not correctly received, the UE feeds back a negative acknowledgement (NACK for short) on a PUCCH. The LTE further supports a carrier aggregation (CA for short) technology, that is, a base station configures multiple carriers for one UE to improve a data rate of the UE. During CA, the multiple carriers sent by the base station are synchronously sent in terms of time. The UE may separately detect and schedule a physical downlink control channel (PDCCH for short) and a corresponding PDSCH of each carrier. A specific detection process of each carrier is similar to that in the foregoing case of a single carrier. The LTE system supports FDD CA, TDD CA, and FDD+TDD CA. The TDD CA is further classified into TDD CA having a same uplink and downlink configuration and TDD CA having different uplink and downlink configurations. In a CA mode, there is one primary carrier and at least one secondary carrier, and a PUCCH carrying an ACK/NACK is sent only on a primary carrier of the UE. When a hybrid automatic repeat request-acknowledgement HARQ-ACK of multiple downlink carriers is transmitted on one PUCCH channel or one PUSCH channel, joint coding is usually used. In the LTE system, uplink control signaling mainly has two coding manners: linear block code Reed Muller (RM for short) and convolutional code. In either coding manner, the base station can perform decoding correctly only when the base station knows a total original information bit quantity of joint coding when using a common decoding manner.
If the total original information bit quantity of the HARQ-ACK joint coding is calculated based on a quantity of PDSCHs on a downlink carrier that are detected by the UE, once a PDSCH on a downlink carrier is missed during detection, a quantity of carriers having PDSCHs that is understood by the UE is less than a quantity of carriers of PDSCHs actually sent by an eNB. However, the eNB does not know whether the UE has missed a PDSCH during detection, and how many PDSCHs are missed during detection. Therefore, the UE and the eNB have inconsistent understandings of the total original information bit quantity of the HARQ-ACK joint coding of multiple downlink carriers. Consequently, a fed back HARQ-ACK cannot be correctly decoded. Therefore, a problem that user equipment and a base station device have inconsistent understandings of a total original information bit quantity (a codebook size of a HARQ-ACK) of a HARQ-ACK of multiple downlink carriers urgently needs to be resolved.